parent *block                      // enclosing block
	lstmt  *ast.LabeledStmt            // labeled statement to which this block belongs, or nil
	labels map[string]*ast.LabeledStmt // allocated lazily
}

// insert records a new label declaration for the current block.
// The label must not have been declared before in any block.
func (b *block) insert(s *ast.LabeledStmt) {
	name := s.Label.Name
	if debug {

	parent *block                         // enclosing block
	lstmt  *syntax.LabeledStmt            // labeled statement to which this block belongs, or nil
	labels map[string]*syntax.LabeledStmt // allocated lazily
}

// insert records a new label declaration for the current block.
// The label must not have been declared before in any block.
func (b *block) insert(s *syntax.LabeledStmt) {
	name := s.Label.Value
	if debug {

	switch s := s.(type) {
	default:
		panic("unreachable")

	case *syntax.DeclStmt, *syntax.EmptyStmt, *syntax.SendStmt,
		*syntax.AssignStmt, *syntax.CallStmt:
		// no chance

	case *syntax.LabeledStmt:
		return check.isTerminating(s.Stmt, s.Label.Value)

	case *syntax.ExprStmt:
		// calling the predeclared (possibly parenthesized) panic() function is terminating

	default:
		panic("unreachable")

	case *ast.BadStmt, *ast.DeclStmt, *ast.EmptyStmt, *ast.SendStmt,
		*ast.IncDecStmt, *ast.AssignStmt, *ast.GoStmt, *ast.DeferStmt,
		*ast.RangeStmt:
		// no chance

	case *ast.LabeledStmt:
		return check.isTerminating(s.Stmt, s.Label.Name)

	case *ast.ExprStmt:
		// calling the predeclared (possibly parenthesized) panic() function is terminating

// the [types.Info] struct for details.
type Object struct {
	Kind ObjKind
	Name string // declared name
	Decl any    // corresponding Field, XxxSpec, FuncDecl, LabeledStmt, AssignStmt, Scope; or nil
	Data any    // object-specific data; or nil
	Type any    // placeholder for type information; may be nil
}

// NewObj creates a new object of a given kind and name.

		// case *DotsType:
		// case *StructType:
		// case *Field:
		// case *InterfaceType:
		// case *FuncType:
		// case *MapType:
		// case *ChanType:

		// statements
		// case *EmptyStmt:
		// case *LabeledStmt:
		// case *BlockStmt:
		// case *ExprStmt:
		case *SendStmt:
			m = n.Chan
		// case *DeclStmt:
		case *AssignStmt:
			m = n.Lhs
		// case *BranchStmt:
		// case *CallStmt:
		// case *ReturnStmt:

// unlabel returns the inner statement for the possibly labeled statement stmt,
// stripping any (possibly nested) *ast.LabeledStmt wrapper.
//
// The second result reports whether stmt was an *ast.LabeledStmt.
func unlabel(stmt ast.Stmt) (ast.Stmt, bool) {
	labeled := false
	for {
		labelStmt, ok := stmt.(*ast.LabeledStmt)
		if !ok {
			return stmt, labeled
		}
		labeled = true
		stmt = labelStmt.Stmt
	}
}

	//
	EmptyStmt struct {
		Semicolon token.Pos // position of following ";"
		Implicit  bool      // if set, ";" was omitted in the source
	}

	// A LabeledStmt node represents a labeled statement.
	LabeledStmt struct {
		Label *Ident
		Colon token.Pos // position of ":"
		Stmt  Stmt
	}

	// An ExprStmt node represents a (stand-alone) expression
	// in a statement list.
	//

		d := s.Decl.(*ast.GenDecl)
		if d.Tok == token.VAR {
			for _, spec := range d.Specs {
				if spec, ok := spec.(*ast.ValueSpec); ok {
					b.add(spec)
				}
			}
		}

	case *ast.LabeledStmt:
		label = b.labeledBlock(s.Label, s)
		b.jump(label._goto)
		b.current = label._goto
		_s = s.Stmt
		goto start // effectively: tailcall stmt(g, s.Stmt, label)

	case *ast.ReturnStmt:
		b.add(s)

	case *ChanType:
		Walk(v, n.Value)

	// Statements
	case *BadStmt:
		// nothing to do

	case *DeclStmt:
		Walk(v, n.Decl)

	case *EmptyStmt:
		// nothing to do

	case *LabeledStmt:
		Walk(v, n.Label)
		Walk(v, n.Stmt)

	case *ExprStmt:
		Walk(v, n.X)

	case *SendStmt:
		Walk(v, n.Chan)
		Walk(v, n.Value)

	case *IncDecStmt:
		Walk(v, n.X)